For his breakout documentary “Super Size Me,” Morgan Spurlock ate nothing but McDonald’s for 30 days. For his concert doc “One Direction: This Is Us,” the filmmaker listened to nothing but the boy band while following and filming Harry, Zayn, Niall, Liam and Louis for six months. How do those two experiences compare?

“It’s addictive,” says Spurlock with a laugh. “Once it gets in your brain it doesn’t go away. I can’t tell you how many nights I woke up singing One Direction songs.”

To most people who aren’t teenage girls, that may sound brutal. The look at the band’s behind-the-scenes goofiness and bond in “This Is Us,” however, proves surprisingly amusing. It’s because One Direction comes off as the down-to-Earth, likable antithesis to, say, the focus of “Justin Bieber: Never Say Never.”

At the Park Hyatt, Spurlock, 42, talked about the difference between One Direction and Bieber, the women who flood hotels in search of 1D and how a One Direction documentary about Morgan Spurlock would turn out.

Everything you hear lately with all the Bieber nonsense going on is, “When anyone is 19, they do stupid stuff and make all these mistakes,” but based on your movie, these guys aren’t going through that. Why is that?The difference between them and Justin Bieber is—there’s a few things. One is I think they’ve been incredibly smart about surrounding themselves with people who will say, “That’s not a good idea.” They aren’t surrounded by “yes” men. I think they’re surrounded by people who question the things they want to do. The band actually gets to make decisions of what happens with the band. They vote democratically, the five of them. “Are we going to add more dates to the tour? Are we going to have matinees? Are we going to have this sponsor? Are we going to do x, y or z?”

How easily do those decisions get made?Well, it’s a democracy. Three out of five decide. Lucky there’s five guys in the band. So once three people vote one way, the decision’s done. And I think the other reason why they’ve had no big [scandalous] moments is because each guy has four other guys that is constantly there to ground them and bring them back and support them.

All of their songs, as far as I know, are about love. We don’t really get much sense of their relationships with young girls from the film, but I’m wondering how much you think they know about love or understand what they’re singing?I think when you’re 19 to 21, or when I was a teenager, you have incredibly idealistic ideas of love. You think things should be perfect or should be in a certain way. Granted they probably have a much more realistic view than other 19-, 21-year-olds because they’re much more worldly now and have really gotten to go out and experience a lot more than other folks. … One of my favorite lines in the whole movie is [by] the girl when we were in Spain, which I think sums up the film and sums up their success so well: “They say what we want to hear but no other boys will say to us.” That’s why they’re successful. Because they say what no other boys will say.

But they’re not writing songs, right?Well, they’re writing songs now with songwriters.

But the previous hits and stuff.For the first album, no. The second album they wrote I think four or five with songwriters. Now on the next album they’re co-writing almost everything with folks.

A question anyone would be thinking when it comes to a popular touring band of young men, especially with millions of women around the world wanting to be close to them, is about their relationships with young women, groupies, that kind of thing. We don’t see that in the film, but I think it’s fair to ask what you observed while you were making the movie because it really speaks to what their lives are like and how they handle all this attention.Yeah. I think they’re really good. There’s women that are chasing them constantly. … There are girls all the time back at the hotels. You’ll go to a hotel and there will be girls that will ride the elevators all night long just hoping for a chance to meet them. That are coming up in the stairwells and banging on the doors and security opens the door and three or four of them will dart through like antelopes. They’re running through the hallways and security’s trying to get them out of the hallways where the guys are. They’re very aware of who they are and where they are, and they’ve been very smart to avoid a lot of the pitfalls that other people have [succumbed to].

Why did you not want to include that stuff in the film? For me that seems like a key component of what it’s like to be in One Direction.Because a lot of the girls that are at the hotel that are chasing them are 12-, 13-year-old girls.

I’m sure there are some 18-, 19-year-olds too though.There are. But for me it’s a gamut of people. There are moms that are at the hotel riding elevators up and down trying to meet the boys. … There are guys in the band who have girlfriends and have had girlfriends and still have girlfriends, and I really wanted to avoid the relationship conversation for a few reasons. One is ultimately who knew if their girlfriends were still going to be around when the movie came out? As you start getting into a real relationship story, how much of that relationship story do you want to tell?

Well, they spend a lot of time in the movie wondering how long they’re going to be around, and that doesn’t stop you from making the movie about them.It’s different. It’s different than me wondering, “Am I still going to have a career?” Versus a girlfriend who’s going to be in the movie who may or may not be a girlfriend at the time and the movie comes out and somebody’s upset that this person’s in the film or the girlfriend’s upset that she’s still in the film when the relationship’s over. So those are two very different animals. That’s why I think one of the things I love in the film is where Liam’s talking about, “I want somebody who can just appreciate me for me.” To suddenly become that successful and now that’s who they see: “Oh my gosh, here’s this very rich, successful pop star. That’s the guy that I want to be with.” To find somebody who doesn’t know who you are, it’s like he’d have to go to Madagascar. They’re probably famous there too. I can’t imagine where you go in One Direction right now where a girl doesn’t know you’re in One Direction.

They’re going to have to tour an island where four people live.[Laughs] Exactly. That’s the place.

Although if there’s only four women there …Yeah. Then it’s like, “Sorry. Sorry. You’re out.” Luckily Zayn’s got a girlfriend, so it would be fine.

They also talk about how they spend all their time together and feel like brothers. Most people would say in that situation brothers are going to have a lot of conflict, spending all day together. But there’s no fighting in the movie. Is that because they don’t fight? There must be some conflict there.The conflict is so few and far between and so rare, stuff they don’t agree on, simply because when they go home, they have time when they go away and they go off and see their families. … Then they don’t see each other. They don’t talk to one another. Then they hook back up when they’re back out on the road. I feel like they love those moments when they’re together because it is such special moments. They’re getting to experience something that 99.999 percent of earth will never get to experience. It’s an incredible thing that’s happening in their lives. So I feel like when they’re together they appreciate that and they appreciate the fact that, “If it wasn’t for these four other guys, I wouldn’t be here.”

It’s a sobering moment when they realize, “This could be as good as our lives ever get, and it’s all downhill from here.” How long do you think they can last?That’s a great question. And what I love about them is they are very self-aware. I think they are very self-aware about where they are. I think they are very self-aware about the music they’re making and how they need to continue to change and grow if they want to stay relevant and stay connected with audiences and fans.

It would be hard to think of a boy band that lasted more than five years ever.But that’s the thing, it depends on how they evolve. Can they evolve in a way where they don’t just seem like a boy band? Where they continue to do something different and age up. When I first met the band last June and I went to the concert--I went to meet them in Charlotte, North Carolina, and when I went to the show, the audience was very young. Eleven-to-16-year-olds was the core audience of the people that were in that show. Then when they started their tour this year in February, the matinees still had very young-skewing audiences. But then the nighttime shows, the 8 o’clock shows suddenly had this mass contingency of 18-to-34 year-old women. Their audience had aged up tremendously, literally in less than a year. I think if they can continue to not only age up their audience but cater to that audience musically … And this new album that they’re working on--you see in the film when they’re recording “Best Song Ever” In the hotel. They’re recording song after song after song while they were traveling through Europe and doing the same thing now in the states. You hear some of the songs and I’m like, “I’d buy that song.” There are songs that they’re making now that are definitely taking them in a much more mature, different direction.

And if Martin Scorsese likes them, any man can feel fine about that.Marty said (in a Martin Scorsese impression), “I like it. I like it. I like your stuff.” Then you know what, maybe we should all give it a shot.

That was a good impression.I’ve been working on it.

If I were De Niro, can you give me how you would direct me?(as Scorsese) “You gotta work a little harder on your lines. You gotta think a little harder. You gotta do a little more. When you get punched in the face, I want you to punch him back. He’s going to punch you; you gotta punch him in the head.”

That was good. I can see you’ve spent some time on that.(as Scorsese) “It’s my Scorsese impression.”

What would a movie be like if One Direction made a documentary about Morgan Spurlock?[Laughs] It’d be the most unwatched movie ever. Would they each take parts? Like each one of them would direct a section so it becomes this omnibus piece of each [one of] five people directing—like “The Five Obstructions.” It becomes like the Lars Von Trier documentary of me made by One Direction. Yeah, a couple people might see that. Not very many.

Well, I feel like they have to do some musical interpretation of your life. How would that go?[Laughs] Very badly. The difference is I grew up the youngest of three ballet-dancing brothers. So I grew up dancing. So my film would actually have some dancing in it, whereas they’re very anti-dancing.

Touche. So they’d have to learn to dance to play you.Or they would just force me to dance as I’m dancing in the film that they’re directing.

As any good documentary filmmaker does.That’s right. “Dance! Dance!”

To what extent does a movie like this have a certain limitation in terms of what it can show? You’re there to get the story and show people something they haven’t seen, but at the same time artists like this, or Katy Perry or whatever, are a brand, and the chances of including something controversial are probably slim. Do you think there’s a limit to what you can deliver with this sort of thing?The whole goal for me in making this film was to make something that gave you a window into their world. Everybody has tough moments, or there were days when we were shooting where somebody didn’t want the camera to be rolling. You’ve gotta give people space. When you’re that much in somebody’s face all the time, and sometimes if somebody’s having a bad day and like, “Listen, I just can’t deal with this right now,” you have to give them that time. So there’s moments where you can push and try to put things like that in the film, but at the end of the day you want to feel like you’re creating something that is going to truly resonate who they are. And I think that’s what this film does. I think the film gives you a real sense into them and into their lives and into what they deal with and takes you on that ride. And it’s fun. I think this movie is so fun, and for me that’s the most important thing.

Was there any agreement beforehand about anything you would or would not do? I’m sure they were a little bit hesitant.The band ultimately, the one thing that they said--and I think the contract they have with Sony is--they said, “We will have the right to remove anything we don’t agree with from the film.” Which there was nothing in the film. There was nothing taken out. The bigger thing was the stuff we put back in. They thought it was important that people know that there was a time that they didn’t get along, when way back in the beginning they almost kicked Zayn out of the band. When that was a conversation that was had. That was something they’re like, “No, this is something that should be in there because people should know that we do have these conversations.” Louis wanted to make sure that when he went home that we saw his grandmother, so we made sure that went back into the family scene.

How much does that impact the way you make the movie? Because obviously this is your movie and they’re in control to a certain extent of what gets in, it must be in the back of your mind a little. “If there’s something I’m curious about that might be seen as controversial, they can just say no.”Ultimately, you have to go to bat for things. For me the goal from the beginning was to make the best movie possible. And that’s all I wanted to do. I wanted to make the absolute best film I could. And I think we did. What you realize is when you’re shooting in the field, you never censor yourself; you never edit in the field. Then you get in the edit room, and you never edit before the film is done. You never remove things before you make the best movie possible. And along the way we’re making cuts, we’re showing the studio, we’re continuing to revise cuts, we’re showing the studio, and then we show the band, and at that point there was nothing in the film that I took out.

Is there anything you’re still wondering about them?The biggest thing for me is I wonder what will continue to happen. For me it’s much more about what’s next. It’s like, “Where are they going? What’s going to happen after this? How long will they be able to sustain?” It’s exhausting. The track that they’re on is a really exhausting track. They’re doing 134 live shows this year. They’re traveling to I don’t even know how many countries in total, how many cities. To be a pop star on the level that they are, it’s work all the time. They’re up, they’re doing press, they’re doing photo shoots, they’re doing interviews, they’re recording their album, they’re going to the arena, they’re coming home after the arena, they’re recording more on the album, and they go to bed. And people are like, “Oh, it’s easy … these guys aren’t doing anything.” But when I look at what I was doing at 19 to 21, as I’m like at a frat party doing a keg stand, here these guys are having an immense amount of responsibility to an army of people.

There’s no time to ride elevators and meet women.[Laughs] Exactly. What are you going to do? For me that’s why a tremendous amount of respect goes to them. Because if I was 19 to 21, I don’t know if I could handle suddenly being thrust into that situation. And it wasn’t even 19. When they went and auditioned for “X Factor” and were put together as a band, they were 16, some of ‘em. Harry was 16 when that started. So between 16 and 19 was where that all happened and now here they are 19, 21. It’s remarkable.

Plus:On Chicago: “I’ve got a bunch of friends that live here, so whenever I’m in town I hang out with them and they take me out to different places. ... I love coming here in the summer, and running down the beachfront is fantastic. Just [to] run down Lake Shore Drive is awesome.”How he get One Direction songs out of his head: “I’m listening to a lot of Robin Thicke going, “Hey hey hey! Hey hey hey hey!” Now that’s being shoved into my head by everybody. … Every time I turn on the radio or walk out of my house now, Robin Thicke is on somewhere. That’s what’s become the dominant musical song surrounding my life right now.”

Watch Matt on “You & Me This Morning,” Friday at 6:55 a.m. on WCIU, the U